Stacked plate-type heat exchangers are known, for example- from DE-A 43 14 808 and DE-A 197 50 748, in each case from the same applicant. This known heat exchanger type in principle uses the same identical plates of single type, in order to achieve a large number of identical parts. This results in the same channel height for the media involved in the exchange of heat, for example oil and coolant, that is the say the same flow cross section. The different heat transfer conditions for the different media can be counteracted by means of different, that is to say matched, turbulence inserts between the plates.
In the case of highly different media, for example liquid and gaseous media, flow channels with a different cross section are required for efficient heat transfer. Two solutions for a stacked plate-type heat exchanger have therefore been proposed in DE-A 195 11 991 from the same applicant, in which a smaller channel cross section is provided for a first medium, for example a coolant in a coolant circuit of an internal combustion engine, than for a second medium, for example the boost air, which has been compressed and heated by a compressor, for the internal combustion engine. In the first solution, only identical plates with the same channel height are used, although two or more channels are connected to be parallel on the boost air side, so that twice the flow cross section, or two or more times the flow cross section is available for the boost air in comparison to the flow cross section for the coolant. According to the second solution, different plate types are used, for example of two types, so that the flow channels through which the boost air flows have approximately twice the channel height of the coolant channels. The two different plate types have rims which are raised at right angles with respect to the plate base and are provided with a step, with the circumferential steps acting as a rest and stop surface for adjacent plates when these plates are stacked. The plate rims are soldered to one another in overlapping, vertically raised areas, for which purpose a defined gap that is subject to relatively narrow tolerances is required, otherwise the soldering is not leakproof. To this extent, this design is characterized by increased manufacturing effort and increased costs.